1. Technical Field
The present invention relates to wireless networks and more specifically to systems, devices and methods for commissioning a wireless network.
2. Background Art
Control networks in homes are increasingly popular installations. A network of sensors and control devices distributed throughout a residential or commercial building may control and provide information for various elements of the building. For example, one or more control networks in a home may control and monitor lighting, heating, ventilation and air conditioning (HVAC), and audio-visual (AV) equipment.
Increasingly, these control networks comprise one or more personal area networks (PANs) organized as a wireless mesh network and in communication with other PANs and the control system. Generally, mesh networks allow each device to communicate with each other thereby providing multiple possible routes between nodes over which a packet can be routed. This is in contrast to traditional networks in which devices generally communicate through a master or a repeater. In mesh networks, each device is a node and may pass communications along to other devices. This increases both the reliability and range of the networks.
Communication protocols govern the operation of these wireless PANs by governing network formation, communication, interferences and other operational characteristics. For example, one such protocol is the Zigbee protocol from the Zigbee Alliance. Another wireless communication protocol is the infiNET EX protocol from Crestron Electronics, Inc. of Rockleigh, N.J. Based on ZigBee PRO technology, infiNET EX is an extremely reliable and affordable protocol that is employed by 2-way wireless wall box dimmers and switches, lamp dimmers and switches plus thermostats and keypads and other sensors and control devices.
Wireless mesh network devices in a Zigbee or infiNET network may be classified as a PAN coordinator, a full function device (FFD) or a reduced function device (RFD). The PAN coordinator is the device which is responsible for starting the formation of a network. There is only one PAN Coordinator in any network. The PAN coordinator chooses the PAN ID, the 16-bit value which is used to uniquely define a PAN.
An FFD is a device which can route communication packets as part of its normal operation. An FFD may also be called a “router”. FFDs form the meshed network topology by establishing communications links to other devices (both FFDs and RFDs). FFDs can act as a sensor or actuator or other type of node.
An RFD is a device which cannot route communication packets. They are always associated with a single FFD and can only participate in the network as an end, or leaf, node.
Wireless mesh networks, such as Zigbee or infiNET networks are formed by an initialization process. Typically, many of configuration properties may be preconfigured prior to initialization. By preconfiguring these properties, an administrator may determine the size and shape of the network. For example, the maximum number of links from the PAN coordinator to the furthest device may influence the shape and size of the network. The maximum number of devices that may connect to a FFD may also determine the shape and size of the network. The PAN coordinator specifies the number of devices that may link to a FFD, as well as how many of these devices may be routers themselves.
The PAN coordinator is responsible for initializing the wireless network. First, the PAN coordinator chooses a suitable radio channel on which to operate.
Next, the PAN coordinator assigns a PAN ID to the network. The PAN ID can be pre-configured or alternatively can be chosen by detecting other networks operating in the same frequency channel and choosing a PAN ID that does not conflict with theirs. The PAN coordinator also assigns a network address to itself. Typically, this address is zero (0).
Once the PAN coordinator is finished configuring itself, it starts itself in PAN coordinator mode. It is then prepared to field queries from other devices wishing to join the network through a commissioning process. Other devices, both FFDs and RFDs, may join the network once the wireless network has been created by the PAN coordinator. The PAN coordinator has the capability to allow other nodes to join. Additionally, FFDs may also allow other nodes to join.
Devices join the network through a commissioning process. First, the new device (i.e. node) scans available channels to find a wireless network. The device then selects a discovered network by choosing a router or network coordinator on that network. Once this is done, the device sends a join message to the desired router or network coordinator, either an FFD on the network or the PAN coordinator.
Often a device will join the first network that it finds. This is less than optimal as the network may not be the desired network, may be an incompatible network. This may lead to a faulty communication link and a suboptimal network mesh.
The desired FFD or PAN coordinator will allow the new device to join the network if it is a permitted device, the FFD or PAN is currently in join mode, and if it has available address space for the new device. The desired FFD or PAN allows the new device to join by assigning it a network address.
There are detractions from the current commissioning process. As mentioned above, crude methods for scanning and joining networks leads to sub-optimal network, increased time to find the correct network and sub-optimal configuration of the network upon joining.
Scan results often arrive in random order with no correlation to distance or suitability. Often the join attempts are made simply in the order the networks are found or worse, one attempt is made with the first network found. Because there is no order of results, the first networks found could be located much further away (and therefore less likely to be correct) than nearby networks. The device may join the incorrect network. As the device attempts to join incorrect networks, the time necessary to join the correct network will increase.
Determining the correct network to attempt to join is important for saving time and aggravation to the installer. Therefore, there is a need for a better commissioning process which includes more robust measures to detect and select networks to join.